Head and Neck Cancer

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261 - 5-Year Results of the Prognostic Roles of Serial Post-Intensity-Modulated Radiation Therapy Undetectable Plasma EBV DNA for Non-Metastatic Nasopharyngeal Carcinoma

Wednesday, October 24
8:15 AM - 8:25 AM
Location: Room 214 A/B

5-Year Results of the Prognostic Roles of Serial Post-Intensity-Modulated Radiation Therapy Undetectable Plasma EBV DNA for Non-Metastatic Nasopharyngeal Carcinoma
V. H. Lee1,2, D. L. Kwong3,4, T. W. Leung3, H. C. W. Choi3, B. O'Sullivan2,5, V. Lai6, C. C. Tong3, K. O. Lam2,3, C. Y. Ng3, S. Y. Chan3, P. P. Ho3, W. L. Chan3, D. K. Leung3, S. K. Chan3, K. C. Tsang3, P. L. Khong6, M. Y. Luk3, and A. W. M. Lee2,3; 1Department of Clinical Oncology,The University of Hong Kong, Hong Kong, Hong Kong, 2Clinical Oncology Center, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China, 3Department of Clinical Oncology, The University of Hong Kong, Hong Kong, Hong Kong, 4Clinical Oncology Center, The University of Hong Kong-Shenzhen Hospital, Shenzhen, Hong Kong, 5Ontario Cancer Institute, Princess Margaret Cancer Centre, Toronto, ON, Canada, 6Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong, Hong Kong

Purpose/Objective(s): We previously demonstrated that post-IMRT 8th week and 6th month undetectable plasma EBV DNA were significant prognostic factors of 3-year survival endpoints for non-metastatic NPC. We now presented our 5-year results. (NCT02476669).

Materials/Methods: Patients with previously untreated non-metastatic NPC confirmed by PET-CT and MRI scans were prospectively recruited from 2010 to 2016. They all had plasma EBV DNA measured at baseline, and then 8 weeks and 6 months following IMRT with/without concurrent +/- adjunct chemotherapy. They were staged and treated based on the 7th edition TNM of AJCC/UICC Staging Classification. Covariates including age, sex, ACE-27, pretreatment LDH and plasma EBV DNA were analyzed by Cox regression for prognostic factors of progression-free survival (PFS), cancer-specific survival (CSS) and overall survival (OS).

Results: 518 patients were prospectively recruited. 71 (13.7%) patients received IMRT alone, while 90 (17.4%) and 357 (68.9%) received concurrent chemoradiation alone and concurrent chemoradiation followed by adjunct chemotherapy respectively. The median pretreatment plasma EBV DNA titers was 494 copies/ml (range 0-175000 copies/ml). After a median follow-up of 5.2 years, 38 (7.3%) and 21 (4.1%) patients still had detectable titers at 8 weeks and 6 months following IMRT. 5-year PFS, CSS and OS in the whole study population were 77.1%, 90.4% and 84.4% respectively. Patients with post-IMRT 8th week and 6th month undetectable plasma EBV DNA titers enjoyed longer 5-year survival endpoints (PFS 79.1% vs. 40.9%; CSS 93.8% vs. 58.8%; OS 85.7% vs. 55.3%; all p<0.001), which were also lengthened for those with post-IMRT 6th month undetectable titers (PFS 78.7% vs. 19.0%; CSS 93.4% vs. 39.7%; OS 85.5% vs. 37.5%; all p<0.001), compared to those who still had detectable titers at the corresponding time points. They are also the only prognostic factors of these endpoints in multivariable analyses (all p<0.001).

Conclusion: Post-IMRT 8th week and 6th month undetectable plasma EBV DNA remained significant prognostic factors after 5 years of follow-up. Additional therapy may have to be considered for those who had persistently detectable plasma EBV DNA after IMRT.

Author Disclosure: V.H. Lee: Honoraria; Roche, Eli Lilly, Pfizer. D.L. Kwong: None. T. Leung: None. H.C. Choi: None. B. O'Sullivan: Partner; University of Toronto. Chair, Prognostic Factors Task Force, TNM Committe; Union for International Cancer Control (UICC). V. Lai: None. K. Lam: Honoraria; TaiHo, Roche. C. Ng: None. S. Chan: None.

Victor Lee, MD

Disclosure:
Compensation
Eli Lilly: Honoraria; Pfizer: Honoraria; Roche: Honoraria

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261 - 5-Year Results of the Prognostic Roles of Serial Post-Intensity-Modulated Radiation Therapy Undetectable Plasma EBV DNA for Non-Metastatic Nasopharyngeal Carcinoma



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